The invention relates to the use of steel alloys in chain pins for hinge conveyor chains, in particular to alloys of stainless steel for use in such chain pins in combination with chain links manufactured from stainless steel.
Stainless-steel hinge conveyor chains are usually deployed in industrial applications where, in mechanical terms, heavy demands are made on the conveyor chains. Thus, stainless-steel conveyor chains can be loaded considerably more heavily than conveyor chains from plastic. They also offer a good resistance to external influences, particularly to the action of dirt and/or (remains of) product to be conveyed, such as for instance to street dirt or other dirt coming from crates when crates are conveyed or to glass fragments (pieces or glass powder) when (reused) bottles are conveyed in, for instance, the beverage industry.
When objects are conveyed by means of conveyor chains, it is sometimes important that the objects can somewhat slide over the surface of the chain. This may be achieved in practice by deploying the stainless-steel conveyor chains either lubricated or unlubricated. The term lubricated is understood to mean that, during the conveyance, a layer of lubricant is applied, usually in the form of an aqueous solution of a (synthetic) lubricant, such as soap. In an unlubricated operation, the surface of the chain needs to be so smooth that a sufficiently low frictional resistance can already be achieved without lubricant.
With both lubricated and unlubricated hinge conveyor chain systems, in use, wear occurs with the passage of time. It has been found that this wear particularly affects the pins which connect the individual links of the chain with each other. Due to the wear of the pin, the conveyor chain will become longer, which inter alia results in skipping of the chain on the driving gear, so that the conveying function is lost. Also, the mutual play between the links which results from wear of the pins will generally lead to more failures in the conveyance, for instance in that, on a worn conveyor chain, products easily fall over or become damaged in another manner. It is even possible for the conveyor chain to break as a result of the wear. In this context, it is noted that the speeds at which the conveyor chains are driven can be very high. In particular if single-line mass transport is desired, for instance after a parallel product flow merges into a single serial flow (for instance in a filling apparatus for bottles), the speed of the single-line chains can increase considerably, to no less than 80 m/min or more.
In addition, high demands are made on the life span of the conveyor equipment. For some applications, a conveyor chain needs to be able to operate without failure for at least six years. For lower speeds, ten years is no exception.